The invention relates to computer graphics, and more particularly to modeling objects for use in computer simulation and animation. More specifically, the invention provides method and apparatus for modeling objects using a genetic plan that specifies, e.g., the behavior of the object and how it interacts with other objects.
Many of us are familiar with the cartoons of the 1930""s and 1940""s. These entertaining animations were painstakingly hand-drawn by graphic artists as a series of still pictures that, when filmed and projected on the movie screen at high speed, provided the illusion of movement. This basic underlying technique of rapidly displaying a series of still frames continues to be used in modern animation, but the way the still frames are generated has been revolutionized by computer graphics. Now, 3D animation can be performed interactively in real time by computers. For example, the fast 3D processing provided by modern video game consoles such as the NINTENDO 64(copyright) can be used to generate realistic animation at high speed in interactive response to a player""s manipulation of input devices such as hand-held controllers. Such advanced video graphics systems provide nearly cinematic quality and realism in real time while permitting all sorts of real and imaginary scenes and characters to be displayed with interactive animation.
One of the challenges to providing realistic interactive high speed 3-D computer animation relates to the manner in which the computer defines display objects. Computers define an object by storing data defining the object""s characteristics. This characteristic-defining data is generally referred to as a model. Most computer graphics animation systems define objects in terms of what the object looks like (i.e., its shape or form). For example, many 3-D graphics systems model a 3D object by defining a number of polygons connected together to define three-dimensional surfaces.
Animated objects move, and therefore have dynamic characteristics in addition to static characteristics. For example, to realistically animate a ball, it is necessary to model the elasticity of the ball (i.e., how much it deforms when it strikes another object such as the ground, a wall or a tennis racket). It may also be necessary or desirable to specify how heavy the ball is (i.e., its mass) so that mathematics can be used to realistically determine its motion under the force of gravity and/or an impact with another surface. Other physical characteristics that are commonly modeled include degree of roughness, the effect of wind on an object, object acceleration in response to stimulus (i.e., how fast the object speed changes), and how the object behaves when it collides with various different types of other objects (for example, a golf ball in a golf game should bounce when it hits the green, become partially buried when it lands in a sand bunker, and sink when it strikes the surface of a pond).
While it is generally known to model the behavior of animated objects, many such prior modeling techniques are complicated, not particularly suited for efficient implementation on small scale systems such as home video game consoles, and have other disadvantages. For example, it can take a long time to prototype animations and games using prior techniques, and the prototyping process may require a high degree of computer programming skill and expertise. Therefore, further improvements are needed.
The present invention solves these problems by providing a general modeling technique for developing animations, simulation and video games. The tools and techniques provided in accordance with this invention can be used by graphic arts designers and animators having little or no computer programming expertise. They can substantially reduce the time required to prototype and develop complex video games, simulations and animations.
In accordance with one aspect provided in accordance with the present invention, an abstract, generic simulation entity definition for use in real time computer simulation and animation encapsulates both the physical and behavioral characteristics of a display object. The simulation entity construct provided in accordance with this invention allows for more accurate modeling of the real world, and supports automation of simulation software production. The present invention thus provides generic, abstract, encapsulated, expandable and maintainable techniques for modeling and animating computer graphics display objects, that allow for a high degree of component reuse from one application to another.
The simulation entity provides a unique xe2x80x9cgenetic planxe2x80x9d containing abstract attributes that may be shared among objects and that may be used to instantiate particular characters for particular animations, games and simulations. Each simulation entity has the knowledge or know-how of common operations, and the ability to communicate with other simulation entities.
In accordance with a further aspect provided by the present invention, two separate class hierarchies are used to differentiate between abstract components and physical components of simulation entities. An entity class hierarchy may be used to specify data structures and methods for behavior and communication. An object class hierarchy may be used to define geometry and animation information and functions. The use of hierarchical classes has the advantage of allowing subclasses be relatively easily derived that inherit properties.
In accordance with a further aspect provided by the present invention, a simulation entity can possess more than one set of object information. This allows the entity to change form (e.g., from a tiger to a bird) or perform multi-functionality during its lifetime.
In accordance with another aspect provided by this invention, a distributed control mechanism genetically builds behaviors into simulation entities. Each simulation entity contains a communication facility (i.e., in-port and out-port), and also its own genetic plan describing the way it reacts to stimuli from the outside world. Since each simulation entity is responsible for its own operations, it may be executed as a separate process (or, in some applications, in a different processor such as a remote computer). The invention supports loose-coupled applications and can be realized as a distributed system.
The abstract data structures/methods provided in accordance with the present invention are general enough to suit tool-kit and run-time software, and may be used to model all sorts of different simulation and animation including a variety of different video game objects (e.g., character, racing, puzzle, etc.) The present invention may provide a general-usage development tool that does not require advanced computer expertise to operate, and yet may be successfully used by artists to rapidly develop animations, games and simulations. The implementation can be used in a variety of different computer applications and platforms including, for example, video games developed for inexpensive home 3D video game platforms.